Insulin Binding: Receptors, Dimerization, and Interactions

Insulin primarily binds to the insulin receptor (INSR), which is a receptor tyrosine kinase. However, insulin can also bind to the insulin-like growth factor 1 receptor (IGF1R) with lower affinity. Insulin-like growth factor 2 receptor (IGF2R) does not bind insulin.

Insulin does form dimers. Each insulin molecule consists of two peptide chains, an A chain and a B chain, held together by disulfide bonds. These chains are derived from a single proinsulin precursor.

Insulin does not naturally form hexamers. However, when injected subcutaneously, insulin can form hexamers in the presence of zinc ions. These hexamers help to slow down the absorption of insulin into the bloodstream, providing a longer-lasting effect.

Insulin can also bind to other molecules, such as insulin-like growth factors (IGFs) and insulin-like growth factor-binding proteins (IGFBPs). These interactions play a role in regulating insulin signaling and its effects on growth and metabolism.